Excessive perspiration is a problem encountered by the amputee population wearing an artificial limb and liner. The liner, which is donned upon the residual limb of the amputee, for both suspension and comfort, can be described as a non-porous elastomeric material with high thermal insulation properties nearly impermeable to moisture, for example, as discussed in the article by Hachisuka at al. (2001) entitled “Moisture permeability of the total surface bearing prosthetic socket with a silicone liner: is it superior to the patella-tendon bearing prosthetic socket?” J. Uoeh, 23, 225-32. An artificial limb liner seals off airflow to the residual limb, which results in an accumulation of sensible and insensible perspiration between the liner and limb.
Accumulation of perspiration adversely affects limb health. Skin irritation and problems such as dermatitis and infection are clinically relevant issues that have long been known to be fostered under moist conditions (e.g. see the article to Barnes (1956) entitled “Skin health and stump hygiene”. Artif Limbs, 3, 4-19); particularly if the liner and residual limb are not cleaned appropriately or frequently. The accumulated perspiration decreases the friction suspending the liner on the residual limb. This can cause a pistoning action, which describes the relative movement between the residual limb and liner.
Excessive limb pistoning leads to friction-related injuries and skin irritation. Examples of such problems are discussed in: Naylor, P. F. (1955) “The skin surface and friction”, Br J Dermatol, 67, 239-46; Naylor, P. F. D. (1955) “Experimental friction blisters”, Br J Dermatol, 67, 327-342; and Akers et al. (1972) “The friction blister”, Military Medicine, 137, 1-7. Such pistoning of the residual limb and artificial limb liner creates the potential for catastrophic failure of the suspension of the limb.
Amputees often complain about the accumulation of perspiration and for good reason. While a few artificial limb users' sweat glands may reduce secretions over time, such a response is neither common nor consistent among all users. To prevent skin problems and to maintain secure adherence, moisture accumulation is currently managed by the amputees themselves. They regularly remove their prosthesis to empty accumulated moisture and dry their limb. An artificial limb system that removes accumulated perspiration would alleviate the conditions that make the skin more susceptible to injuries while achieving a lasting secure adherence. It might also improve their quality of life. A survey of lower limb amputees (n=90) found that perspiration inside the prosthesis was one of the five most common reason for a reduced quality of life during the summer months, as discussed in Hagberg et al. (2001) “Consequences of non-vascular trans-femoral amputation: a survey of quality of life, prosthetic use and problems”, Prosthet Orthot Int, 25, 186-94.
The current state of technology relative to moisture management in a modern artificial limb is fundamentally lacking. An artificial limb liner is donned on the amputee's stump creating an airtight seal from which the artificial limb is suspended. Sensible and insensible perspiration is trapped between the residual limb and liner in this sealed system until a build-up of moisture necessitates complete removal and “airing” of the stump.
There is a need for an approach to reduce perspiration build up in a suspension and comfort liner used in an artificial limb. The approach should also improve secure adherence by limiting relative motion between the liner and residual limb and thus mitigate pistoning.